Method of manufacturing bolts.



, H. T. FRAUENHEIM. METHOD OF MANUFACTURING BOLTS.

APPLICATION FILED MAYH, 1913.

Patented May 9,1916.

WITNESSES INVENTOR HARRY 'I'. FRAUENHEIM, OF PITTSBURGH, PENNSYLVANIA,ASSIGNOR TO KERNEB MANUFACTURING COMPANY, OF PITTSBURGH, PENN$YLVANIA,A. CORPORATION OF PENNSYLVANIA.

METHOD OF MANUFACTURING BOLTS.

Application filed May 17, 1913.

To all whom it may concern Beit known that I, IIABRY T. FRAUEN- I-IEIM,a citizen of the United. States, residing at Pittsburgh, in the countyof Allegheny and State of Pennsylvania, have invented a new and usefulMethod of Manufacturing Bolts, of which the following is a full, clear,and exact description, reference being had to the accompanying drawings,forming part of this specification, in which Figure 1 is a sectionalperspective view, largely conventional, showing one form of heatingfurnace which I may use in carrying out my invention; Fig. 2 is aperspective view, also largely conventional, showing one form ofupsetting and welding dies; Fig. 3 is an elevation, partly in section,and illustrating the manner in which the stay bolts are twisted; andFigs. 41 and 5 are elevations showing apparatus for threading the bolts.Figs. 3, 4 and 5 are also largely conventional. Fig. 6 is a plan view ofa track bolt made in accordance with my invention.

My invention has relation to a novel method of making stay bolts and thelike of the general character described and claimed in the patent ofEthan I. Dodds, No. 1,121,173, issued December 15, 1914, and also trackbolts and the like of the general form described and claimed in thepending application of Ethan I. Dodds, Serial No. 7 59,916, filed April9th, 1913. The stay bolts consist of solid threaded end heads, which areconnected by two bar members, which are twisted upon each other throughan angle of at least 180 degrees. The track bolts consist of a bodyportion composed of a plurality of separable bar members twisted uponeach other to an angle less than 180 degrees, and upset and welded atone end to form a flanged head, and welded and threadedat the oppositeend.

p In making my improved stay-bolts, I preferably proceed as follows :Itake two bar members preferably of staybolt iron, and pile them togetherto form a cylindrical blank. In the drawing I have shown each of theblanks as made up of two semicylindrical members 2. These blanks arethen inserted in a suitable furnace, and are locally heated toapproximately a sweating heat, at which the end portions of the barmembers will begin to unite. The furnace should be Specification ofLetters Patent.

Patented May 9, 1916..

Serial No. 768,286.

of such character that only the end portions of the members which are tobe upset to form the head of the bolt will be heated to an appreciableextent. In Fig. 1 I have shown, moreor less conventionally, a suitablefurnace for this purpose. This furnace, which is a gasfired furnace, isindicated at 3. 4 designates the opening through which the gas isdelivered to the heating chamber of the furnace, and 5 is the outletopening leading to a stack, not shown. The heating chamber of thefurnace is provided with a stepped wall 6, and the opposite wall isprovided with a plurality of openings 8 through which the blanks to beheated are inserted. The distance between the face of the stepped walland the opposite wall is just sufiicient to expose within the furnacethe desired length-of the blanks to'be heated, while the rest of thelength of the blank being either in the wall or outside the furnace walldoes not become heated to an objectionable extent.

After heating, the piled blank is withdrawn from the furnace. and itsheated end is simultaneously upset and welded by the action of suitabledies, Fig. 2 shows more or less conventionally dies which may be usedfor this purpose. In this figure, 9 designates a sectional die blockbetween which the heated ends of the blanks are clamped, and which areformed with die cavities into which the said ends extend. By the actionof a suitable plunger, such as shown at 11, the upsetting or welding toform the heads 12 is effected. The die cavities 10 should be larger thanthe diameter of the head desired, preferably by at least one-sixteenthof an inch, in order to compensate for the losses in scale when weldingtogether a plurality of separate bar members, and also for losses bysubsequent machining before threading. After forming one or both ofthe-heads 12 in the manner described, the blank is then twisted throughan angle of at least 180 degrees. In accordance with my invention thetwisting of the bar members is effected after one end of the blank hasbeen heated and upset in the manner described, and before heating andupsetting the opposite end. This twisting may be effected by anysuitable means. In Fig. 8 I have shown the headed end of'the blank asheld in suitable clamp 13, while a twisting die 14 is applied to theopposite end portion thereof. After the twistingoperation,

the other end of the blank is then heated in I been continuouslythreaded from one end to the other and the intermediate portion of thebar then turned off toremovethe threads of such portion. This threadingmay be effected by first advancing one of the heads 12 while in asuitable lathe into a suitable threading die 15, as shown in Fig. 1.After this head has been threaded, the blank is reversed end for end,and the opposite end portion is then threaded in the same or a similardie, as indicated in Fig. 5. The usual telltale holes, not shown, maythen be drilled longitudinally through one or both heads into eachconnectingbar member.

My invention provides for the rapid, economical and eflicientmanufacture of stay bolts of this character. It provides a bolt having ahighdegree of flexibility with respect to vibration strains due torelative movements-ofthe sheets in which the two ends of the bolt areinserted in use, while at the same time it has a high degree ofresistance to compression and tension strains.

In service, the bolt is subjected to vibrations and gyratory movementsdue to the movements of the plates on the boiler which are connected bythe bolts. Owing to the twisting of the barmembers through at least 180degrees, the points of greatest bending stress during these movementswill be shiftedthrough the bar members instead of being localized nearone end of the bolt, as is the case with ordinary bolts. Consequently,the life of the bolts is greatly extended. The

7 twisting of the bar members through an angle of at least 180 degrees,also gives the bar the necessary stiffness in securing it in place.

I have found that if fouror more bar members are used in forming thebolt, the latter will not give the desired resistance to the strains towhich it is subjected. It is also difficult to insert it in place, sinceafter one head has been partly screwed into place and the screw threadson the other head be- 7 gin to. engage the other sheet or plate, the

torsion in applying will twist the bolt slightly and cause it to bind sothat it cannot be completely inserted. With four or more connecting barsdifficulty is also experienced in threading, on account of the liabilityof head. After the bolts are inserted in place,

the slightly projecting head portions must be peened over or headedslightly to retain them in place and make, tight joints. Where four ormore bar members are employed, this action distorts and injures thebolt, since its diameter is limited to certain established standards andthe cross-section of the bar members cannot therefore be increased.

By using two of the bars, however, their cross-section is suliicient togive the desired resistance to strains in making, as well as in applyingand in use. This cross-section is also sufficiently large to properlycontain the telltale holes without unduly weakening the bar members.These telltale holes are necessarily of a fixed diameter, determined bythe Government standards, and these are fully met by the bolts formed bymy invention, in which either two or three bar members are twisted inthe manner described. Furthermore, by using two bar members, they willremain together in pile form during heating, whereas, it would bedifficult to hold a greater number together while heating them and whileinserting them into the upsetting and welding dies. It will be furthernoted that my improved method leaves undisturbed the original scaled orrolled surfaces of those portions of the bolts between the heads. Thisgives a much better surface for resisting the action of water than wherea machined surface is exposed. The natural skin formed on the barmembers during their manufacture is not cut away or disturbed, andconsequently, the stay bolt is much stronger.

By the term stay bolt as used herein, and in the claims, I do not intendto restrict the use of my invention to bolts for boilers, as it isobviously adapted to the manufacture of various bolts of this generaltype.

The method of manufacturing headed bolts, such as shown at 15 in Fig. 6,is similar to that above described, except that the bar members aretwisted upon each other less than 180 degrees, and only one end of theblank is upset, viz., the end which forms the flanged head 16. The otherends of the members are simply welded and threaded. The twisting of thisform of bolts is less than 180 degrees because it is desired that thebolts shall not be rigid under tension stresses but shall be capable ofsome elongation un der excess strains.

I claim 1. The herein described improvement in the manufacture of bolts,having a head and a twisted portion formed of separate members, whichconsists in forming a head on one end of the bolt blank, then twistingthe same, and then welding together said separate members at theopposite end portion of the blank; substantially as described.

2. The herein described improvement in the manufacture of bolts, havinga head and a twisted portion formed of separate mem- In testimonywhereof, I have hereunto set bers, which consists in forming a head onmy hand.

one end of the bolt blank then twisting the same, and then Weldingtbgether said sepa- HARRY FRAUENHEIM' rate members at the opposite endportion of Witnesses:

GEO. B. BLEMING,

the blank and upsettin them to form a head JEssE B. HELLER.

at that end; substantia 1y as described.

monies of thie patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

